Sartre contributed many other strands of existential exploration, particularly in terms of emotions, imagination, and the person's insertion into a social and political world. He became the father of existentialism, which was a philosophical trend with a limited life span. The philosophy of existence on the contrary is carried by a wide-ranging literature, which includes many other authors than the ones mentioned above. There is much to be learned from existential authors such as Karl Jaspers (1951, 1963), Paul Tillich, Martin Buber, and Hans-Georg Gadamer within the Germanic tradition and Albert Camus, Gabriel Marcel, Paul Ricoeur, Maurice Merleau-Ponty and Emmanuel Lévinas within the French tradition (see for instance Spiegelberg, 1972, Kearney, 1986 or van Deurzen-Smith, 1997). Few psychotherapists are aware of this literature, or interested in making use of it. Psychotherapy has traditionally grown within a medical rather than a philosophical milieu and is only just beginning to discover the possibility of a radical philosophical approach.

Sartre's philosophy

Many critics argue Sartre's philosophy is contradictory. Specifically, they argue that Sartre makes metaphysical arguments despite his claiming that his philosophical views ignore metaphysics. Herbert Marcuse criticized Being and Nothingness (1943) by Jean-Paul Sartre for projecting anxiety and meaninglessness onto the nature of existence itself: "Insofar as Existentialism is a philosophical doctrine, it remains an idealistic doctrine: it hypostatizes specific historical conditions of human existence into ontological and metaphysical characteristics. Existentialism thus becomes part of the very ideology which it attacks, and its radicalism is illusory".

Existentialism says existence precedes essence. In this statement he is taking existentia and essentia according to their metaphysical meaning, which, from Plato's time on, has said that essentia precedes existentia. Sartre reverses this statement. But the reversal of a metaphysical statement remains a metaphysical statement. With it, he stays with metaphysics, in oblivion of the truth of Being.